Fire extinguishing process



3,276,999 FllRE EXTINGUISHHNG PRUCESS Roland Petit, Paris, Claude Kaziz, La Courneuve, and Georges Wetroii, Le Thillay, France, assignors to Produits Claimiques Pechiney-Saint-Gobain, Neuillysur=Seine, France N0 Drawing. Filed July 9, 1963, tier. No. 293,378 Claims priority, application France, July 12, 1962, 903,763 t Claims. (Cl. 252-8) This invention relates to a fire extinguishing composition and more particularly to the use of the compound bromo- I-difiuoro-1,1-ethane, alone or in admixture with other components, in the extinguishing of fires and to a new and improved method for the preparation of such fire extinguishing compound.

In the extinguishing of fires, and especially burning hydrocarbon, it is known to make use of halogenated hydrocarbon derivatives, the most effective one to the present being methyl bromide. However, methyl bromide finds numerous objections in a use of this type by reason of its toxicity and dangers which arise in its use. Fire extinguishing characteristics somewhat comparable to methyl bromide, but less toxic than methyl bromide, have been demonstrated by other certain bro-motluorinated derivatives such as bromotrifluoromethane and bromochlorodifiuoromethane but the vapor pressures of these compounds are so high at ambient temperature as to make it necessary to employ air-tight containers of high strength for the housing of such materials. lems arise in the storage of such materials, for use is incapable of being made of low cost, prefabricated containers which are easy to handle.

It is an object of this invention to provide a halogenated hydrocarbon derivative which can be used effectively and efficiently in the extinguishing of fires but which is not subject to the objectionable characteristics of compounds heretofore described and it is a related object to provide a method for the preparation of the halogenated hydrocarbon derivative and the use thereof in extinguishing fires.

More specifically, it is an object of this invention to provide a method for producing a halogenated hydrocarbon derivative which is as effective as methyl bromide in the extinguishing of burning hydrocanbon or other fires; which is relatively non-toxic; which has a vapor pressure sufficiently high at ambient temperature to enable packaging in commercially available, low cost containers; which can be easily stored in containers for use without the build-up of excessive pressures; and which can be used in admixture with other halogenated hydrocarbon r derivatives of the type previously used in fire extinguishers to provide a synergistic eifect which alleviates the undesirable characteristics of such other fire extinguishing compounds without detracting from their fire extinguishing properties.

It has been found, in accordance with the practice of this invention, that the compound bromo-l-difluoro-1,1- ethane has fire extinguishing power which is comparable to that of methyl bromide and which, by reason of its relatively high boiling point of 14-15 C. at atmospheric pressure, is relatively free of the risks of gaseous leakage, explosion or the like, and it is capable of being housed in readily available, low cost containers which can be easily handled in the extinguishing of fires. The compound is also characterized by relative high stability and freedom from decomposition under normal storage conditions.

The bromo-l-d-ifluoro-1,1-ethane can be used alone as a fire extinguishing compound or it can be used in admixture with other halogenated hydrocarbon derivatives, such as the following, which are given by way of Thus delicate prob- Patented Oct. 4, 1966 illustration, but not by way of limitation, but in which the bromo-l-difluoro-l,l-ethane is present to constitute at least 25% by weight and preferably 50% by weight of the compostion:

dichlorodifluoromethane chlorodifluoromethane =bromotrifluoromethane bromochlorodifluoromethane The bromo-l-difluoro-l,l-ethane can be used alone or in admixture with one or more of the other halogenated hydrocarbon derivatives as a fire extinguisher with gaseous propellants, such as nitrogen, carbon dioxide and the like.

Bromo-1-difluoro-l,1-ethane is not a new chemical compound. It has previously been produced by reaction of a bromide with a metallic salt such as the silver salt of difluoropropionic acid at a temperature of about 0 C. It has also been produced by reaction of a hydrobromic acid with vinylidene fluoride whereby a reaction product is secured containing mostly bromo-Z- difluoro-l,1-ethane, with only a small proportion of the desired bromo-l-difluoro-l,lethane. Since the raw materials for these reactions are quite expensive, the described methods for preparation are not considered commercially desirable.

Thus it is also an object of this invention to provide a new and improved means and method for the preparation of bromo-l-difluoro-1,1-ethane of low cost and readily available materials and in high yields.

Brorno-l-difluoro-l,l-ethane can be prepared, in accordance with the improved process of this invention, by a vapor phase reaction of difluoro-1,1-ethane with bromine at a temperature within the range of 350500 C. and preferably at a temperature within the range of 400-450 C.; cooling the reaction product to a temperature below 40 C. and preferably to a temperature within the range of 1S40 C. leaving the desirable bromo-ldifluoro-1,1-ethane and other halogenated hydrocarbon derivatives in the uncondensed state along with formed hydrobromic acid and unreacted bromine; removing the formed hydrobr-omic acid and unreacted bromine; and finally separating the bromo-l-difiuoro-1,l-eth-ane from the remainder by techniques well known to the art, as will hereinafter be described.

For the reaction in the gaseous phase, the ingredients are provided in the molar ratio of 1 mole bromine to 0.5-1.2 moles of difluoro-l,l-ethane and preferably in the ratio of 1 mole bromine to slightly less than 1 mole difiuoro-1,l-ethane. The reaction is carried out for at least 5 seconds and preferably for a period within the range of 10-30 seconds. For the removal of hydrobromic acid and unreacted bromine from the portions which remain uncondensed when the reaction product is cooled to a temperature below 40 C., the uncondensed portions are treated with an alkaline solution, such an aqueous solution of potassium hydroxide. The remainder can thereafter be dried and separated by conventional means to isolate bromo-l-difiuoro-l,l-etl1ane in a relatively pure state.

The fol-lowing examples are given by Way of illustration, but not by way of limitation, of the practice of this invention:

EXAMPLE 1 Preparation of bromo-I-difluor0-1,1-ethane A gaseous mixture of 0.915 mole bromine per mole of difiuoro-l,l-ethane is passed through a glass tube having a length of 40 cm. and an internal diameter of 4 cm. housed within an electrically heated enclosure having a temperature of about 425 C. The flow rate of the gaseous mixture is calculated to provide for exposure to reaction of about 15 seconds.

The gaseous reaction products issuing from the reactor tube are advanced through a jacketed heat exchanger refrigerated with a water coolant to a temperature below 40 C. after which the cooled gases are washed in two wash bottles with a 10% aqueous solution of sodium hydroxide to remove the formed hydrobromic acid and unreacted bromine.

The washed gases are dried by passing them through a drying column packed with pellets of calcium chloride and sodium hydroxide in admixture. The dried gases are condensed in a cooled trap at a temperature of about 80 C. The condensate contains about 84% by weight bromo-1-difluoro-1,1-ethane and about 16% by weight difluorodJ-ethane. The condensate is processed in a fractional distillation column to effect separation of the bromo-l-difluoro-l,l-ethane from the remainder.

The conversion rate of difluoro-1,l-ethane to bromo-ldifluoro-1,1-ethane is in the order of about 75% and the molar yield in bromo-l-d-ifiuoro-l,l-ethane is calculated to be about 85%.

EXAMPLE 2 Fire extinguishing tests For tests of the fire extinguishing power, use was made of a cylindrical tank formed of sheet iron having wall thicknesses of 0.15 cm., an internal diameter of 35 cm., and a height of 10 cm. The cylindrical tank has a capacity for 3 liters of hydrocarbon fluid in the form of F grade petrol having a distillation fraction out which boils between 110 C. and 160 C. and a density of 0.742 at 15 C., which fluid is used as the fuel in the tests.

The fire extinguisher used was a cylindrical container of steel having a capacity of 0.2 liter and which was loaded with 280 grams of bromo-1-difluoro-1,1-ethane and suflicient nitrogen to obtain an internal pressure 8 kg./cm. at ambient temperature.

The petrol was ignited and one minute later the bromo- 1-difluoro-1,1-ethane was supplied onto the fire through a nozzle in the container. The hydrocarbon flame was extinguished within 3 seconds which was less time than required to empty the extinguisher (about 4 seconds).

EXAMPLE 3 An aluminum extinguisher fitted with an impact discharge valve and having a capacity of 0.4 liter was charged with the following fire extinguishing composition:

Grams Bromo-l-difiuoro-l,l-ethane 80 Teepol 26 Glycol 3 2 Water 54 Dichlorodifluoromethane 160 The pressure within the container was in the order of about 2.5 kg./cm. at ambient temperature.

When the fire extinguishing test was conducted, as in 4 Example 2, but with the composition of Example 3, the petrol fire was extinguished within 2.5 seconds while the container continued to spray for an additional 4.5 seconds before becoming emptied.

It will be apparent from the foregoing that we have provided a new and safe process for the extinguishing of fires in which use is made of bromod-difluoro-Llethane as an essential component of the fire extinguishing composition and that We have provided a new and improved method for the commercial production of such brorno-l-difluoro-l,l-ethane.

It will be understood that changes may be made in the details of formulation and operation without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. The process for extinguishing fires comprising applying to the -fire a composition, an essential component of which is l-bromo-l,l-difiuoro-ethane present in an amount within the range of 25 to percent by weight of the composition.

2. The process as claimed in claim 1 in which the composition includes a gaseous propellant selected from the group consisting of nitrogen and carbon dioxide.

3. The process as claimed in claim 1 in which the composition include-s a halogenated hydrocarbon selected from the group consisting of dichlorodifluoromethane, chlorodifluoromethane, hromot-rifluoromethane and bromoch-lorodifluoromethane.

4. The process as claimed in claim 1 in which the composition includes a halogenated hydrocarbon selected from the group consisting of dichlorodifluoromethane, chlorodifluoromethane, bromotrifiuoromethane and bromochlorodifluoromethane and a gaseous propellant selected from the group consisting of nitrogen and carbon dioxide.

References Cited by the Examiner UNITED STATES PATENTS 866,437 9/1907 Davidson 2528 2,021,981 11/1935 Bichowsky 252-8 X R 2,653,130 '9/1953 Eiseman 252-8 2,668,419 2/ 1954 Mapes 252-8 XR 2,678,953 5/1954 Conly 2528 XR 2,757,212 7/ 1956 Cleaver et al 260-653 2,897,151 7/1959 Bickett 252 8 2,972,637 2/ 1961 Tullock 260-653 FOREIGN PATENTS 878,854 2/1943 France.

OTHER REFERENCES Freon Technical Bulletin B2, Dupont, Wilmington 98, Del. (1962), page 6 relied upon.

LEON D. ROSDOL, Primary Examiner. JULIUS GREENWALD, Examiner.

M. WEINBLATT, Assistant Examiner. 

1. THE PROCESS FOR EXTINGUISHING FIRES COMPRISING APPLYING TO THE FIRE A COMPOSITION, AN ESSENTIALLY COMPONENT OF WHICH IS 1-BROMO-1, 1-DIFLUORO-ETHANE PRESENT IN AN AMOUNT WITHIN THE RANGE OF 25 TO 100 PERCENT BY WEIGHT OF THE COMPOSITION. 